<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <title>天气案例_深度监视</title>
    <script type="text/javascript" src="../../vue.js/vue.js"></script>
  </head>

  <body>
    <div id="root">
      <h2>今天天气很{{info}}</h2>
      <button @click="changeWeather">切换天气</button>
      <hr />
      <h3>a的值是:{{numbers.a}}</h3>
      <button @click="numbers.a++">点我让a+1</button>
      <h3>b的值是:{{numbers.b}}</h3>
      <button @click="numbers.b++">点我让b+1</button>
      <button @click="numbers = {a:666, b:888, c:{d:{e:200}}}">
        彻底替换掉numbers
      </button>
      {{numbers.c.d.e}}
      <h3>{{arr}}</h3>
      <button @click="addHandler">数组索引变更数组</button>
      <button @click="arr.push('新加的')">数组方法变更数组</button>
    </div>

    <script type="text/javascript">
      Vue.config.productionTip = false;

      const vm = new Vue({
        el: "#root",
        data: {
          isHot: true,
          numbers: {
            a: 1,
            b: 1,
            c: {
              d: {
                e: 100,
              },
            },
          },
          arr: ["123", "456"],
        },
        computed: {
          info() {
            return this.isHot ? "炎热" : "凉爽";
          },
        },
        methods: {
          changeWeather() {
            this.isHot = !this.isHot;
          },
          addHandler() {
            this.arr[this.arr.length] = "新来的";
            console.log(this.arr);
          },
        },
        watch: {
          isHot: {
            handler(newValue, oldValue) {
              console.log("isHot被修改了", newValue, oldValue);
            },
          },

          // #region监视多级结构中某个属性的变化
          // "numbers.a": {
          //   handler() {
          //     console.log("a被改变了");
          //   },
          // },
          // #endregion

          // 监视多级结构中所有属性的变化
          numbers: {
            deep: true,
            handler() {
              console.log("numbers改变了");
            },
          },

          arr: {
            handler() {
              console.log("arr被改变了");
            },
          },
        },
      });
    </script>
  </body>
</html>
<!-- 
		深度监视:
				(1).Vue中的watch默认不监测对象内部值的改变(一层).
				(2).配置deep:true可以监测对象内部值改变(多层).
		备注:
				(1).Vue自身可以监测对象内部值的改变,但Vue提供的watch默认不可以!
				(2).使用watch时根据数据的具体结构,决定是否采用深度监视.
	-->
